A Midland magistrate has lost the latest round in his bid to sue his daughter-in-law for slander and libel over an allegation that he assaulted her and his baby grandson.

Three appeal judges upheld a High Court ruling, in October last year, that JP Richard Westcott’s claim should be struck out, as both an oral complaint and a written statement to the police made by Dr Sarah Westcott, the estranged wife of Mr Westcott’s son Edward, were protected by absolute privilege.

Deputy Judge Richard Parkes QC said that he should maintain the balance struck by the House of Lords in an earlier case and give priority to the need to protect those who give evidence to the police, and to encourage them to speak freely without the fear of being sued in defamation for doing so.

Lord Justice Ward, sitting with Lord Justice Sedley and Lord Justice Stanley Burnton, said that it was a “sad and sorry domestic dispute which has now blown up out of all proportion”.

“Perhaps the wife will rue making the complaint; perhaps father-in-law will rue not accepting the police’s refusal to act as sufficient to assuage his wounded dignity, for here they are in the Court of Appeal.

“What a great shame for these intelligent parties that the public have been invited into their drawing room.”

Mr Westcott, of Wheelgate, Wyre Piddle, Pershore, Worcestershire, was interviewed but not prosecuted over the alleged incident in March 2005 and was concerned that he had not had a chance to clear his name over the allegations which were known to his colleagues and to Worcester Social Services, said his counsel Ken Craig.

As a result, Mr Westcott, who maintained that the allegations were wholly false, claimed that his blameless character had been compromised and he had been restricted in obtaining access to grandson Daniel, who was six-months-old at the time of the alleged assault.

Dr Westcott, who has obtained a decree nisi from her husband, alleged that trouble flared when she took Daniel to the home of Mr Westcott and his wife, Heather, for a Good Friday visit to his father.

She said that during an exchange over her changing the locks and Edward having a key, Mr Westcott “flipped” and lashed out as she held Daniel in her arms.

Dr Westcott, of Roberts Lane, Chalfont St Peter, Buckinghamshire, took her son to hospital for a check-up but neither of them had any visible injuries.

Lord Justice Ward said that, because society expected that criminal activity would be reported and when reported investigated and, when appropriate, prosecuted, all those who participated in a criminal investigation were entitled to the benefit of absolute privilege in respect of the statements which they made.

He added: “In my judgment, any inhibition on the freedom to complain will seriously erode the rigours of the criminal justice system and will be contrary to the public interest.

“In my judgment, immunity must be given from the earliest moment that the criminal justice system becomes involved.

“It follows that the occasion of the making of both the oral complaint and the subsequent written complaint must be absolutely privileged.”

Lord Justice Stanley Burton commented that Mr Westcott “has a degree of vindication by virtue of the decision of the CPS (Crown Prosecution Service) that the evidence was insufficient to create a reasonable prospect of his conviction, and a man is considered to be innocent unless proved guilty.

“That must be sufficient for him.”

Mr Westcott, who was not in court, was ordered to pay the costs of the appeal and refused permission to take his case to the House of Lords.